Put the potatoes in a pan of boiling salted water and simmer for 15 mins until cooked, then drain.

Put the onion and fennel in a bowl, cover with the lemon juice and set aside.

Mix half the lemon zest with the mustard, honey and oil. Place the trout, skin-side down, on a baking tray lined with parchment.

Brush the mustard glaze over the trout and bake in the oven for 10 mins until just cooked and starting to flake.

2)Once the potatoes are cool enough to handle, slice them into 1 cm-thick pieces and tip into a large bowl.

Mix the remaining lemon zest with the soured cream, dill, parsley and some seasoning.

Spoon over the potatoes and stir through. Add the onion and fennel, and mix gently.

Sprinkle the reserved fennel fronds over and serve with the trout.